Poncet now finds himself in Isfahan, capital of Persia, practicing medicine in the court of the Shah. In order to rescue his old friend Juremi, imprisoned in the Urals, Poncet travels in disguise to Russia, where he engages in a diplomatic duel of wits with Peter the Great. The friends, reunited, are captured by nomads and sold as slaves in Afghanistan. This the beginning of Poncet's circuitous return to Isfahan, where his wife and daughter are trapped inside the walls by a besieging army of the Afghan king, Mahmud.

Subtle, erudite, exciting, and beautifully crafted, this is historical fiction that belongs on the shelf beside the work of Patrick O'Brian.